GLTF runtime dynamic textures

Questions
1

I’m trying to change textures at runtime. I exported my models from blender to GLTF with seperate textures and binary files. How does GLTF encode which mesh the textures belong to?

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2

Each mesh has a material property, and in material you can find map - which is probably the texture you are looking for (mind that map is an instance of Texture, not an url or image data.)

3

Note that there’s nothing glTF-specific about changing the textures on a material: All of the three.js documentation about Scenes, Meshes, and Materials can be used regardless of the model format. THREE.TextureLoader can be used to get new textures from a URL.

4

Thanks for your reply. So, I have loaded a texture into a material and applied that material to a mesh object. The problem is that I had to apply the texture to each mesh because I don’t know how to identify which texture belongs to which mesh. I just traversed the scene and set the material for each mesh. Which is wrong.

5

Yes, but does the texture object have any reference to which image it came from?

6

The Texture does not keep any list of which Materials it was originally attached to — if you need that, you would want to store it before you change the texture out.

Note that if you enable the “Custom Properties” option when exporting from Blender, any key/value data you put onto objects should be preserved as object.userData in three.js. This could be helpful for sending information from Blender to your code in three.js, e.g. to store a list of texture names to (later) download and attach to that object.

7

That’s good to know. I’m new to all of this but my assumption was that somehow the glTF file encoded this information that I’m after (which textures belong to which meshes). I just can’t find anywhere in the spec that says how.

8

The only association in what GLTFLoader returns is what three.js’ API has:

  • mesh.material (Mesh -> Material reference)
  • material.map, material.roughnessMap, etc… (Material -> Texture reference)

The texture does not have references to meshes, you’ll need to create that from the information above.

The glTF spec works the same way: meshes have materials, and materials have textures. To get a list of all meshes that have materials using a particular texture, you have to work backwards.

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9

Thanks man that should do it